More new articles

[bh480@scn.org]

From: Ben Creisler bh480@scn.org

Here are some articles I don't recall seeing mentioned yet:

Van Valkenburgh, B. & R. E. Molnar. 2002. Dinosaurian and 
mammalian predators compared. Paleobiology 28 (4): 527-543.
ABSTRACT
 Theropod dinosaurs were, and mammalian carnivores are, 
the top predators within their respective communities. 
Beyond that, they seem distinct, differing markedly in 
body form and ancestry. Nevertheless, some of the same 
processes that shape mammalian predators and their 
communities likely were important to dinosaurian predators 
as well. To explore this, we compared the predatory 
adaptations of theropod dinosaurs and mammalian 
carnivores, focusing primarily on aspects of their feeding 
morphology (skulls, jaws, and teeth). We also examined 
suites of sympatric species (i.e., ecological guilds) of 
predatory theropods and mammals, emphasizing species 
richness and the distribution of body sizes within guilds. 
The morphological comparisons indicate reduced trophic 
diversity among theropods relative to carnivorans, as most 
or all theropods with teeth appear to have been 
hypercarnivorous. There are no clear analogs of felids, 
canids, and hyaenids among theropods. Interestingly, 
theropods parallel canids more so than felids in cranial 
proportions, and all theropods appear to have had weaker 
jaws than carnivorans. Given the apparent trophic 
similarity of theropods and their large body sizes, it was 
surprising to find that species richness of theropod 
guilds was as great as or exceeded that observed among 
mammalian carnivore guilds. Separation by body size 
appears to be slightly greater among sympatric theropods 
than carnivorans, but the magnitude of size difference 
between species is not constant in either group. We 
suggest that, as in modern carnivoran guilds, smaller 
theropod species might have adapted to the threats posed 
by much larger species (e.g., tyrannosaurs) by hunting in 
groups, feeding rapidly, and avoiding encounters whenever 
possible. This would have favored improved hunting skills 
and associated adaptations such as agility, speed, 
intelligence, and increased sensory awareness.

Senter, P. 2002. Lack of a pheromonal sense in phytosaurs 
and other archosaurs, and its implications for 
reproductive communication. Paleobiology: 28 (4): 544-550
ABSTRACT
 The vomeronasal (VN) system is a pheromone-processing 
sensory system of tetrapods. Tetrapods use pheromones to 
communicate territorial boundaries, reproductive status, 
sex, and species identity. Presumed impressions of VN 
bulbs on phytosaur frontals led to a claim that phytosaurs 
possessed the VN system. However, in extant crocodilians, 
which lack the VN system, the corresponding impressions 
are associated not with cerebral tissue but with the 
ophthalmic nerves. Phytosaur head morphology was not 
conducive to pheromone collection. The extant phylogenetic 
bracket suggests that all extinct archosaurs, including 
phytosaurs, lacked the VN system. Without the pheromonal 
sense, they would not have used chemical means to convey 
territorial boundaries, reproductive status, sex, and 
species identity. Instead, they would have used visual, 
acoustic, and tactile cues, as in extant archosaurs and 
other tetrapods in which the VN sense is reduced or absent.

Frey, E, Marie-Céline Buchy, Wolfgang Stinnesbeck, and 
José Guadalupe López-Oliva, 2002. Geosaurus vignaudi n.sp. 
(Crocodyliformes: Thalattosuchia), first evidence of 
metriorhynchid crocodilians in the Late Jurassic 
(Tithonian) of central-east Mexico (State of Puebla) 
Canadian Journal of Earth Sciences. 39(10): 1467-1483 

Abstract: Thalattosuchian crocodilians of the genus 
Geosaurus have mostly been recorded from the Jurassic of 
Europe. A single species was reported from Argentina. Here 
we describe a new species of Geosaurus vignaudi from the 
middle Tithonian La Pimienta Formation of State of Puebla, 
Mexico. Diagnostic for this species are the extremely low 
tooth count and a rostroventrally directed process at the 
rostral terminus of the mandible combined with a pair of 
horizontally directed rostral teeth. The skull of the 
holotype shows bite marks that probably caused the death 
of the animal.